1. Field of the Invention
This invention relates to a color printer, fax machine, photocopier, or other image formation device which forms images using electrophotographic technology, and in particular relates to an image formation device enabling switching between a color printing mode and a monochrome printing mode, and which moreover affords increased flexibility in mounting a developing unit in the monochrome printing mode.
2. Description of the Related Art
Image formation devices which form images using electrophotographic technology, provided for example in color printers, have an image carrier in which is formed an electrostatic latent image according to image data; a charging unit which charges the outer surface of the image carrier; an exposure unit which exposes the outer surface of the charged image carrier according to image data, to form an electrostatic latent image; a developer device which supplies toner, as a developing agent, to the electrostatic latent image to develop a toner image; and a transfer unit which causes the toner image to be transferred to a media. The developer device detachably holds a plurality of developing units which house color toners, and has a developer unit holder which causes the appropriate developer unit to be brought into proximity with the image carrier according to the development timing. This developer unit holder is normally a rotatably controlled developing rotary. When performing color printing, development units with color toner in a plurality of colors, for example, four colors (yellow or Y, magenta or M, cyan or C, and black or K) is mounted in the developing rotary. When performing monochrome printing using only black toner, a black development unit is mounted in the developing rotary.
An image formation device has been proposed which can be put into a color printing mode in which a four-color development unit is mounted, or into a monochrome printing mode in which only a black development unit is mounted, with the user able to switch between the two modes as appropriate. Such an image formation device has been proposed in, for example, Japanese Patent Laid-open No. 2003-43773 (Publication Date: Feb. 14, 2003), Japanese Patent Laid-open No. 2003-316106 (Publication Date: Nov. 6, 2003), and Japanese Patent Application No. 2003-160059.
In Japanese Patent Laid-open No. 2003-43773 and Japanese Patent Application No. 2003-160059, an image formation device is disclosed in which the color printing mode is set when four color development units are mounted in the developing rotary, and the monochrome printing mode is set when a single black development unit is mounted only in the mounting position for the black development unit of the developing rotary, with no development units mounted in the other mounting positions, which are CMY positions.
In Japanese Patent Laid-open No. 2003-316106, an image formation device is disclosed in which the mounting positions in the developing rotary are not in fixed one-to-one correspondence with development units in four colors, and a development unit of an arbitrary color can be mounted in an arbitrary mounting position. In this image formation device, information on the color of the developing agent is read from memory provided in the development unit, to detect which color development units are mounted in which positions of the developing rotary, and based on the detected positions, rotation of the developing rotary is controlled in the development process. Specifically, in Japanese Patent Laid-open No. 2003-316106, when development units in the four CMYK colors are mounted, the device operates as a color printer, and when only the black development unit is mounted, the device operates as a black monochrome printer.
Further, an image formation device has been proposed in which, by mounting black development units in all four of the mounting positions of the developing rotary and setting the monochrome printing mode, the number of times development units need to be replaced can be reduced. Such an image formation device is disclosed in Japanese Patent Laid-open No. 2002-351190 (Publication Date: Dec. 4, 2002). In this image formation device, by mounting four black development units in the four mounting positions of the developing rotary for color printing, reading memory provided in the development units, detecting the mounting positions, color information, and amount of toner remaining, and by using the black development units in order, the frequency of replacement of development units in monochrome printing mode can be reduced, even for small-type development devices.